1. Field of the Invention
This invention relates to a movable, protective, sawdust collection hood for use with a table saw equipped with a rotary saw blade and, more particularly, to such a hood that provides a directed air stream for removal of sawdust generated by a saw blade rotating on a shaft located below a work table.
2. Background Art
Protective hoods have become widely used to remove sawdust generated by the cutting of a work piece on a rotary table saw, and to conduct the dust toward a sawdust collection receptacle. The hoods have additionally served to protect the user thereof from injury due to inadvertent contact with a rotating saw blade. Such hoods have generally taken the form of a longitudinally elongated enclosure, open at the bottom, having a pair of spaced-apart vertical walls joined at their upper edges by a top wall, and adapted for placement over an exposed, upper peripheral portion of a saw blade, the saw blade being mounted for rotation on a shaft located below the work table of the table saw. Protective hoods of this kind have been configured such that air was drawn into the hood through an air intake opening (due to an air current created by rotation of the saw blade and/or by an attached vacuum or blower system), from whence air streamed across the blade and out a discharge opening toward a sawdust collection receptacle, carrying the sawdust away with it. Retractable apparatus was provided to support the hood in position over the saw blade for example, by a link arm having one end attached to the hood and an opposite end attached to a splitter mounted to the table saw behind the saw blade. Attached to a front portion of the vertical walls was a forwardly inclined nose having horizontal leading and trailing edges, such that rearward advancement of a work piece toward and against the nose panel caused the hood to rise, and with further such movement of the work piece the trailing edge of the nose rested on and made sliding contact with an upper surface of the work piece. An example of protective hoods of this kind is disclosed in U.S. Pat. No. 4,576,072 to Terpstra et al. An alternative retractable support for such a protective hood, i.e., a parallelogram linkage and counterbalance mechanism, was disclosed in U.S. Pat. No. 4,875,398 to Taylor et al.
Such heretofore known protective hoods, however, failed to adequately remove sawdust and chips generated at the final stage of a cutting operation. Initially, during a cutting operation, so long as a work piece progressed rearwardly under the hood, across the upper surface of the work table and past the saw blade, sawdust and chips generated within the hood remained confined within the hood to be carried away by the air stream within the hood. But, after the cutting of a work piece had progressed to the stage at which the forwardmost portion of the work piece had moved underneath and rearward of a front portion of the hood, a gap was created between the hood and the work piece, thereby permitting sawdust and chips to be thrown forward through the gap and to escape from the hood. My invention overcomes this problem by eliminating the gap at the final stage of cutting a work piece.
According to the present invention there is provided a protective, sawdust collection hood for a table saw. The table saw is equipped in conventional fashion with a saw blade mounted for rotation on a shaft located below a horizontal work table, and having an exposed, peripheral portion thereof extending above the worktable and rotating toward the front side of the work table. The table saw is also equipped with a splitter mounted directly behind the saw blade. In a first embodiment, the hood is adapted for pivotal attachment to the splitter, whereby the hood can be moved between a retracted, storage position and a working position directly over and straddling the exposed portion of the saw blade. The hood includes a pair of spaced-apart, vertical side panels, each side panel having a front, central and rear portion. A forwardly inclined nose panel is mounted between front portions of the side panels, and has horizontal leading and trailing edges. An upper cowl is mounted between the side panels, and has a substantially vertical, front portion terminating at a forward edge that engages an upper surface of the nose panel, and has a rearwardly extending, upwardly inclined portion terminating at a rear edge. A lower cowl is mounted between the side panels below the upper cowl and has a substantially vertical, front portion and rearwardly extending, substantially horizontal, central and rear portions. The front portion of the lower cowl terminates in a horizontal forward edge disposed above the trailing edge of the nose panel. A pair of vertical side skirts are provided, each of the skirts being movable between a first, lowered position and a second, raised position, and means are attached to the side panels for suspending a side skirt from each of the side panels. In this first embodiment, each of the side skirts has a substantially vertical slot, and the means for suspending the side skirts include a slot pin attached to and extending laterally outward from a central portion of the adjacent side panel, retainer means attached to each slot pin for retaining the pin within the slot, and stop means attached to the side skirts for limiting the downward movement of the side skirts when the hood is raised away from the work table. The side panels, upper cowl, lower cowl, and side skirts are made of a rigid transparent material so that an operator of the table saw can see through the hood to monitor cutting operations.
During the initial stages of cutting a work piece, the side skirts are in the lowered position, the lower edge of each skirt being just even with the trailing edge of the nose panel. As the work piece is then moved rearwardly across the work table toward and against the nose panel, the hood rises until the trailing edge of the nose panel rests upon an upper surface of the work piece, thereby completing the initial stage. There then follows an intermediate cutting stage, wherein the work piece progresses rearwardly toward and past the saw blade with the trailing edge continuing to rest on, and make sliding contact with an upper surface of the work piece. During the intermediate stage, the side skirts remain in the lowered position. The final cutting stage occurs when the forwardmost portion of the work piece has been moved rearward underneath the side skirts and has fully cleared the nose panel; at that time the nose panel drops down to the work table, thereby closing the gap that would otherwise exist between the upper surface of the work table and the hood, and the side skirts move up into the raised position. Thereafter, once the work piece has fully cleared the saw blade and the side skirts, the side skirts also drop down from the raised position to the lowered position and come to rest on the work table. The cut having been completed, the cut portions of the work piece can then be removed from the work table.
Throughout each of the stages of cutting a work piece, sawdust is carried by a directed stream of air away from the situs of cutting within the hood and toward a sawdust collection receptacle. Air enters the hood through an intake opening defined by rear portions of the side skirts and a rear portion of the lower cowl, thence streams forward over the work piece and saw blade and through an orifice defined by the forward edge of the lower cowl, the trailing edge of the nose panel and the front portions of the side panels, and thereafter is conducted rearwardly between an upper surface of the lower cowl and a lower surface of the upper cowl to exit the hood. In this manner, sawdust and chips generated by cutting a work piece, including that generated in the final stage of cutting, remains confined within the hood while being conducted toward a collection receptacle.
Although rotation of the saw blade is sufficient to create the above-described air stream, the air stream flow rate can be increased by attaching a vacuum source to the hood. Therefore, in a preferred embodiment, the hood further includes a rear discharge wall mounted between an upper surface of a central portion of the lower cowl and the rear edge of the upper cowl. The rear discharge wall has an air discharge hole. A vacuum hose adapter is attached to a rear surface of the rear discharge wall and is aligned with the air discharge hole. A vacuum hose having one end connected to the adapter, and an opposite end attached to a shop vacuum or other vacuum source, provides vacuum suction to the hood for increased air flow through the hood.
In a second embodiment of the hood, the hood is pivotally attached to the splitter by two pairs of parallel, equal-length links, forming a parallelogram linkage. In this embodiment, each of the slots in the side skirts is arcuate and the above-described means for suspending the side skirts further includes a first pair of parallel, equal-length, skirt support arms disposed on opposite sides of the hood, each of said support arms having a first end pivotally attached to a side panel and a second, opposite end pivotally attached to a front portion of a side skirt; and said means further includes a second pair of parallel, equal-length, skirt support arms disposed on opposite sides of the hood, each of said support arms having a first end pivotally attached to a side panel and a second, opposite end pivotally attached to an upper rear portion of a side skirt.
In a third embodiment, the hood further includes a vacuum conduit assembly for drawing sawdust and wood chips away from the saw blade and through the hood to a collection receptacle. A collar joint is provided for pivotally attaching a rear portion of the hood to the vacuum conduit assembly, which permits rotation of the hood about a horizontal axis between a raised, storage position and a lowered, working position. The vacuum conduit assembly comprises a vacuum source connected to an electric power source; a laterally disposed, elongated, cylindrical, hollow boom having an intake end and an opposite discharge end; a hollow, cylindrical head stock mounted to the intake end of the boom and coaxial therewith, said head stock having an intake duct extension in communication with the interior of the head stock, and said intake duct being attached to, and in communication with, the collar joint; a movable vacuum hose within the boom, having a first, intake end storable within the head stock, and an opposite, discharge end with an attached hose end ring seal that is slidable within the boom; and a stationary vacuum hose having one end attached to the discharge end of the boom and an opposite end attached to the vacuum source. In this manner, a vacuum created by the vacuum source is communicated through the stationary and movable hoses to the head stock and thence to the hood.
The collar joint comprises a first, semicylindrical, partial collar attached to an intake end of the vacuum conduit assembly, said partial collar being axially-aligned on a lateral axis Axe2x80x2xe2x80x94Axe2x80x2 and extending between rear portions of the side panels, and said collar having longitudinally-aligned, front and rear openings. The collar joint further comprises a second, semicylindrical, partial collar that partially surrounds and engages the first partial collar. The second partial collar is rotatable about the lateral axis Axe2x80x2xe2x80x94Axe2x80x2 and about a front, exterior surface of the first partial collar. The second partial collar is mounted between a rear edge of the lower cowl and a rear edge of the upper cowl, and is laterally disposed between rear portions of the side panels. The second partial collar has an air discharge hole that is in register with the front opening of the first partial collar when the hood is in a working position directly over and straddling the saw blade. A collar pin is laterally inserted along axis Axe2x80x2xe2x80x94Axe2x80x2 through the rear portions of the side panels, through tab projections from the intake end of the vacuum conduit assembly, and through the first and second partial collars. Preferably, the boom comprises a stationary portion and, in telescoping relation thereto, a laterally movable portion. The laterally movable portion of the boom is attached to the head stock. A rack and pinion assembly couples the laterally movable portion to the stationary portion of the boom, thereby permitting lateral adjustments of the position of the hood with respect to the saw blade and fence. A normally-closed, momentary switch, wired in series with the vacuum electric power source, is mounted on the head stock, such that, whenever the hood is moved to the raised, storage position adjacent the head stock, the momentary switch is opened, thereby de: energizing the vacuum source. For locking the hood in the raised, storage position, the nose panel has a retainer aperture engagable by a spring catch mounted on the head stock. The head stock is provided with a removable cap, whereby, with the cap removed, the intake end of the movable vacuum hose may be withdrawn from the head stock and used to vacuum clean the table saw and its immediate environs, and thereafter replaced inside the head stock.
Important objectives of the present invention therefore include the following:
It is an object of the invention to provide a protective hood for a rotary table saw that carries sawdust and chips away from the situs of cutting and toward a sawdust receptacle, even during the final stage of cutting a work piece.
It is a further object of the invention to provide such a protective hood that is movable between a retracted and a working position directly over and straddling the saw blade.
The above and other aspects and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the drawings.